My child hates their stepparent and isnt kind to them for good reason. Bioparent married to stepparent refuses to give that child any money for school.
Im sorry your wife has been so ill and I know that is stressful. However, the child needs to either be working or in school (or a bit of both). This might not mean a 4 year school. I think you and your wife need to sit down with the oldest and really explain the rules and expectations of the house. Perhaps if they are working, that you would be willing to pay half of tuition for a semester at a local college and if they pass all their classes you re-evaluate?